The present invention relates to a device for feeding and positioning a recording medium in a radiographic apparatus, and more particularly to a device capable of feeding a recording medium smoothly to an exposure unit, fixing the recording medium therein, and reliably feeding the exposed recording medium to a device for reading out radiation-image information in a so-called vertical radiographic apparatus.
Vertical radiographic apparatus form radiation images of substantially upstanding objects. The prior vertical radiographic apparatus operate by separating x-ray films supplied to a prescribed position one by one, feeding the x-ray film with rollers and endless belts to a front end plane of an exposure unit, namely an exposure plane which projects from the main body of the radiographic apparatus, and inserting and positioning the x-ray film between a pair of intensifying screens fixed at the exposure plane for exposure.
With the conventional radiographic apparatus, however, the x-ray films are fed by the rollers and the endless belts along a path having a small radius of curvature and extending from the main body of the radiographic apparatus to the exposure unit and also extending in a region where the x-ray film is to be inserted between the intensifying screens. Therefore, the x-ray film as it passes through such a path is subjected to a strong bending stress, which is not preferable.
The rollers and the endless belts are disposed in the vicinity of each of upper and lower portions of the exposure unit for feeding the x-ray film from the main body of the radiographic apparatus to the exposure plane of the exposure unit and then withdrawing the exposed x-ray film from the exposure plane. These rollers and endless belt have made the exposure unit large in size.
The radiographic apparatus includes a jaw rest positioned upwardly of the exposure unit for supporting the jaw of a patient to allow him to be x-rayed in an upstanding position. Since the rollers and the endless belt are disposed within the exposure unit near its upper end, however, the distance from the jaw rest to a leading end of the x-ray film in the exposure position is increased to thereby limit an effective exposure region, so that a body area which can be x-rayed is restricted.
There has in recent years been proposed a system in which a radiation image is reproduced by storing radiation image information temporarily in a sheet comprising a so-called stimulable phosphor, scanning the sheet by stimulating rays to cause the stimulable phosphor carrying the radiation image information stored therein to emit light in proportion to the radiation energy stored, detecting the emitted light and converting it into an electric signal for image reproduction (see U.S. Pat. Nos. 4,258,264, 4,276,473, and 4,315,318, for example).
The stimulable phospor in the proposed system is a provisional recording medium for temporarily storing radiation image information. The stimulable phospor can repeatedly be used by discharging any residual radiant energy after the radiation image information has been read, according to a process shown in U.S. Pat. No. 4,400,619, Japanese Laid-Open Patent Publication Nos. 56-11392 or 56-12599, for example.
Therefore, the vertical radiographic apparatus in the foregoing radiation image information recording and reproducing system should preferably comprise a radiation image information recording and read out apparatus composed of read out means for reading radiation image information stored in the stimulable phosphor sheet and erase means for discharging any residual radiant energy from the stimulable phosphor sheet. It is preferable for the stimulable phosphor sheet or provisional recording medium to be capable of repeated use in the radiation image information recording and read out apparatus.
The upstanding radiation image information recording and read out apparatus constructed to meet the above demands will suffer from a greater problem when a strong bending stress is imposed on the stimulable phosphor sheet than when a strong bending stress is applied to the x-ray film because the stimulable phosphor sheet is thicker and much more rigid than the x-ray film. The problem of bending of the stimulable phosphor sheet is of much importance since it is supposed to be used many times unlike the x-ray film.